Sudden Death in Infants is ill-understood and presently tends to be attributed to malfunction of the nervous system. The hypothesis that a mechanical defect in the maturation of the larynx may be involved is proposed for study. The gross anatomy of the larynx at birth differs substantially from the adult, but the stages of maturation of the morphological structures and of their mechanical modes of functioning have not been specified. The objectives of this project are to characterize the morphological horizons of laryngeal maturation and the associated biomechanical maturation. The material for this investigation is drawn from victims of the Sudden Infant Death Syndrome and from a parallel series of deaths due to other causes in the first year of life, in order to define the major developmental horizons throughout infancy. The force-deformation characteristics of the various elastic structures at entrance of the larynx are measured in autopsy specimens. Some entire specimens will be subjected to serial section and x20 photographic enlargements will be used as the basis for reconstructions in which the relation between anatomical measurement and elastic behavior will be studied.